Mayor Bloomberg has snagged the support of a third GOP county leader, effectively assuring him of the party line in November, sources said yesterday.

The sources said that Bronx GOP leader Jay Savino, once an outspoken critic of the mayor’s decision to turn independent, has decided to sign on with Bloomberg’s re-election campaign.

With GOP leaders in Brooklyn and Staten Island already on board, the mayor seems assured of winning enough votes among the executive members of the Republican county committees in all five boroughs to get the permission he needs to run on their line.

“When this is all over, he could wind up with most of the votes,” said one source.

Bloomberg surrendered his Republican Party registration when he was considering running for president last year.

For months, those in the anti-Bloomberg camp have been pinning their hopes on the mayor not getting any major ballot lines.

That would have forced him to run as an independent on a new line far removed from the immediate eyesight of voters.

Political insiders scoffed at the scenario from the start, and predicted that Bloomberg would eventually win back Republican and Independence party defectors.